This invention pertains to a pressure and vacuum relief valve and particularly, to such a valve constructed to have debris-catching openings.
Although it is anticipated that this invention could be used in various applications, the preferred embodiment is intended for use with irrigation lines. It is common practice in irrigating large fields, particularly with sprinkler-type irrigation, to employ a supply line extending along one edge of a field. From this supply line, lateral lines extend across the field. Standpipes with sprinkler heads are attached to the lateral lines for irrigation of an elongate strip of the field. The lateral line is periodically moved from one lateral outlet to another to effect irrigation of the entire field.
Between irrigations the various lines are drained of water. As the water supply is turned on, the resident air must be vented in order to allow the water to fill the lines. Since the valves at the lateral junctions are normally closed one or more of them must be opened to allow the air to escape.
Pressure and relief valves have been developed in order to overcome this problem. Such a valve, when closed, allows air to escape through apertures in a seal-forming disc. When water from the supply source comes in contact with the valve, the air-bleeding apertures are closed by a flexible web which is forced against the disc.
After irrigation, water is drained from the lines. As the water pressure is removed, the web flexes away from the disc. This allows air from the lateral line to replace the water in the supply line. A vacuum, which would otherwise develop, is thereby prevented. Thus, as irrigation lines are drained and filled, air automatically fills and empties the lines as necessary to accommodate the corresponding movement of water within the lines.
However, one problem inherent in the pressure and vacuum relief valve system just described is the plugging of the relief valve mechanism with debris carried in the water. During filling, as water surges through the supply lines and into a valve, some of the water escapes through the relief valve aperture before the web closes. It is debris carried in this water which may become lodged in the relief valve. When this happens, a complete seal is prevented and water leaks into the lateral line.
It is the purpose of this invention to provide a pressure and vacuum relief valve which overcomes the problem of the prior art described above.
Specifically, it is an object to provide such a relief valve which provides for the capture of such debris before it can get into the seal-forming components of the valve.
It is also an object of this invention to provide such a device which incorporates the debris-catching feature into the flexible web, thereby precluding the requirement for adding other devices to a valve beyond the minimum required.
Such a device is provided by the preferred embodiment of this invention. It includes a resilient aperture-closure web which, when in a relaxed condition, forms a cavity in cooperation with the aperture-containing disc. Openings in the web and the apertures communicate with the cavity to form a passageway for air when water is not in the valve body. When water under pressure comes into the body, that pressure causes the cavity to collapse, closing the aperture. Any debris in the water is caught in the openings before it can get into the cavity or the aperture.
These and additional objects and advantages of the present invention will be more clearly understood from a consideration of the drawings and the following detailed description of the preferred embodiment.